The present invention relates generally to the field of bladder control devices. More particularly, the invention relates to the field of bladder control devices in which a valve is provided to control flow from the bladder of a patient.
Bladder control devices related to the field of this invention include devices such as those disclosed by Kulisz et al., in U.S. Pat. No. 5,512,032 and U.S. Pat. No. 5,701,916. The former patent discloses a bladder control device including a valve which remains open under the influence of flow through the device in accordance with Bernoulli's Principle. The latter patent discloses proximally and distally disposed retainers for retaining the bladder control device within a patient's urethra. These pioneering devices can be activated in an intuitive way by a patient, simply by the patient increasing bladder pressure. The valve remains open at a lower pressure so long as a certain minimal flow rate through the valve continues. When the flow subsides, the valve closes.
Intraurethral bladder control devices are disposed within the urethra during use. Consequently, patients and their physicians desire that the diameter of the device be limited without compromising the performance of the device. It can be appreciated that larger diameter bladder control devices could cause some discomfort during insertion and use. Scaling down a device, i.e., making a smaller device having the same configuration, will reduce the flow through the device exponentially. Reducing flow through the valve limits the force creatable by the Bernoulli's Principle to hold the valve open. Additionally, if the diameter of a compression spring, as used in the prior devices to bias the valve close, is scaled down, the spring is subject to buckling, which could leave the valve in a permanently open position.